74 THE RATTLE-SNAKE TRIBE, 



bite. The principal distinguishing rule in these 

 tribes is, that the venomous Serpents have only two 

 rows of true or proper teeth (that is, such as are 

 not fangs) in the upper jaw, whilst all others have 

 four. 



A head entirely covered with small scales is also 

 in some degree a character, but bv no means an uni- 

 versal one, of poisonous species ; as are also scales on 

 the head and body furnished with a ridge or promi- 

 nent middle line. The number of poisonous Ser- 

 pents is very few when compared with the whole 

 number of the species. Out of about 230 species 

 described in Systema Nature there are not 40 that 

 have been discovered to possess the poisonous 

 fangs. 



All the species cast their skins at certain periods 5 

 and those of cold and temperate climates lie con- 

 cealed in a torpid state during winter. The flesh of 

 several of the Serpents is innoxious, and even eaten 

 by the natives of many countries. Some of them 

 deposit eggs, which are connected in a kind of chain; 

 and others produce their young perfectly formed 

 from eggs hatched within their bodies. 



THE RATTLE-SNAKE TRIBE. 



The animals of this tribe, which are very few, arc 

 all furnished with poisonous fangs, but their bite is 

 not fatal unless they happen to be much irritated. — - 



